The registration and inspection system for domestic waste water treatment systems was introduced under the Water Services (Amendment) Act 2012. The purpose is to protect ground and surface water quality from the risks posed by malfunctioning systems. The Act was a response to address the European Court of Justice ruling against Ireland in October 2009. Each water services authority is required to establish and maintain a register of domestic waste water treatment systems situated within its functional area.
Domestic waste water treatment systems include all septic tanks, waste water tanks, and treatment systems receiving, storing, treating or disposing of domestic waste water. All owners of premises connected to a domestic waste water treatment system are required to register their systems in line with the Domestic Waste Water Treatment Systems (Registration) Regulations 2012 (S.I. No. 220 of 2012), as amended by Domestic Waste Water Treatment Systems (Registration) (Amendment) Regulations 2013 (S.I. No. 180 of 2013). This includes owners of properties which are let, whether private landlords or local authorities etc., and employers who provide living accommodation to employees. All buildings, caravans, mobile homes, and other structures connected to a domestic waste water treatment system must be registered. Details of each individual property must be provided separately. A Certificate of Registration is required when the owner is selling or transferring ownership of a property. The certificate of registration is valid indefinitely.
Protect Our Water is an online registration system for domestic waste water treatment systems. The registration process captures whether the owner is a private individual or a company as well as the name and address of the owner and the address of the property being registered. The Water Services Authority (local authorities) in which the property is located is also required.
A domestic waste water treatment system means a system involving physical, chemical, biological or thermal processes, or a combination of such processes, utilised for the treatment or disposal of domestic waste water, or the sludge derived from domestic waste water, and includes:
(a) All septic tanks and waste water tanks and systems receiving, storing, treating or disposing of domestic waste water and all drains associated with such tanks or systems, and
(b) All drains associated with the discharge of domestic waste water, whether or not they discharge to a septic tank or waste water tank.
The CSO receives a new file from the Local Government Management Agency every year. The registrations file includes all properties back to the inception of the registration regime in 2012. For the purposes of this statistical release, the CSO has defined a new registration as a property that was first registered in 2017 or later and in the annual data file corresponding to the year of registration. A small number of late registrations may be included under this definition.
The CSO has reallocated the location of a small number of properties to a different county. These changes apply particularly to properties registered as located in a Dublin postal district area with an owner address in a rural area. The reallocation is based on the premise that the correspondence and location addresses were transposed. The owner details are taken into account in this process e.g. no change was made if the owner was a local authority or if the location was a building site. All remaining properties located in a Dublin postal district area have been allocated to Dublin.
The Domestic Waste Water Treatment Systems 2023 release shows revisions when compared with corresponding figures in previous releases due to a change in methodology. In previous releases, registrations in early months of the year following the reference year were included and classified as existing registrations. The methodology for the 2023 release has been revised to exclude these registrations. As a result, there was a small decrease in annual total registrations and existing registrations for pre-2023 figures compared with previous releases.
The CSO used the company name information on the register to allocate systems to Domestic, Public authority, or Other non-domestic. Local authorities, schools, etc. were classified as Public Authorities. The Other non-domestic category contains a broad range of companies including stud farms, financial institutions, golf clubs, building companies, etc.
The CSO Census of Population collects information from households on type of sewerage system. In 2022 there were 467,331 individual septic tanks and 59,066 other individual treatment systems recorded. This is around 8% higher than the number reported in the 2022 Protect Our Water file. The latter includes domestic and non-domestic owners (used by employees etc.). Two separate family units sharing the same septic tank would be reported twice in the Census if they completed two separate Census forms whereas this would be recorded as one system in Protect Our Water. Rural apartment buildings that are not connected to the public sewerage network should have ticked the Other sewerage facility response on the Census form and should not be included in Protect Our Water.
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